1. Field of the Invention
This invention relates generally to a technique for recording data from a processor unit and, more particularly, to a method and apparatus for selecting and providing a set of instrumentation signals for locomotive testing and diagnostic purposes.
2. Discussion of the Related Art
A typical locomotive employs a locomotive control computer (LCC) that controls the operation of the locomotive, and an inverter control computer (ICC) that controls a power inverter to provide command signals to a set of alternating current (AC) motors driving the locomotive. In one design, the LCC and the ICC are implemented in the locomotive as separate hardware modules, where the ICC is part of a processor unit such as a multiple processor unit (MPU) module. In that case, the LCC and ICC are configured to communicate with each other via use of a serial (point-to-point) link by reading and writing data to a dual-port (shared) memory (e.g., a dual-port RAM), physically located in the ICC. Accordingly signals transmitted between the LCC and ICC are generally those needed for locomotive control functions such as torque and speed references and feedbacks, fault information and speed calibrations.
Currently, a diagnostic user interface to the LCC, such as a LCC monitor program, is implemented in the LCC to enable a user to download diagnostic signals (diagnostics) and instrumentation signals concerning LCC operation for testing purposes and the like. Unlike the LCC however, the ICC does not have a comparable monitor program function to provide a diagnostic user interface to the ICC for purposes of enabling the user to download diagnostics and instrumentation signals concerning ICC operation for testing purposes and the like. Rather, the dual-port memory, via the LCC, is currently the only option available to enable the user to communicate with the ICC for testing and diagnostic purposes.
In order to accommodate engineering testing and diagnostics of the ICC, provisions have been made in the ICC module hardware design to include an optional instrumentation daughterboard that accesses pre-selected ICC instrumentation signals provided via ICC software located in the ICC. The instrumentation daughterboard is configured to enable user access to thirty-two instrumentation signals provided by the ICC software; sixteen pre-selected hardware signals and sixteen pre-selected software instrumentation signals out of many more than sixteen possible software instrumentation signals. Because there is no direct diagnostic user interface implemented in the ICC however, the set of sixteen software ICC signals are pre-selected during the original programming of the ICC software. As a result, if a different set of sixteen software instrumentation signals is required, such as for debugging a performance problem, it is necessary to rebuild and reload the ICC software into the ICC at significant expense and time.